A video appearing to show seven French citizens, including four children, kidnapped in Cameroon last week has been posted on YouTube.

In the video, posted on Monday, a male hostage says the group was taken by Nigeria’s Boko Haram group, who are demanding the release of other members jailed in Nigeria and Cameroon.

“We have been taken by Jama’atu Ahlis Sunna Lidda’awati wal-Jihad,” one of the male hostages said in the video, referring to the name in Arabic of Nigeria’s Boko Haram militants. “They want the liberation of their brothers in Cameroon and their women imprisoned in Nigeria.”

The kidnapping on Tuesday of the seven French nationals in Cameroon’s far north, near the border with Nigeria, highlighted the risk to French citizens in Africa since Paris sent troops into Mali to oust Islamists there.

“The president of France has launched a war on Islam,” said one of the apparent kidnappers, warning the hostages would be killed if their demands were not met.

France’s foreign ministry said it was still trying to verify the authenticity of the video. Cameroon’s communication minister Issa Tchiroma Bakary said he could not comment because his government was not aware of the video.

The governor of Cameroon’s Far North Region, Augustine Fonka Awa, said he was not aware of any Boko Haram members being held in the country.